1. Field of Invention
The present invention relates to cryopreservation and more particularly to an apparatus for sealing a cryovial by contracting a thermally contractible film thereon by heating such that liquid nitrogen is prevented from permeating through the cryovial in a subsequent cryopreservation.
2. Related Art
Cryopreservation, is a process where biological specimens (e.g., cells, whole tissues, sperms, etc.) are contained in cryovials and then preserved by placing in liquid nitrogen by cooling to low sub-zero temperatures, such as −196° C. (the boiling point of liquid nitrogen). At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death is effectively stopped. However, when vitrification solutions are not used, the specimens being preserved are often damaged due to freezing during the approach to low temperatures, warming to room temperature, or liquid nitrogen permeating through cryovials (the most serious one).
It is often that liquid nitrogen held at very low sub-zero temperature may permeate through cryovials during cryopreservation. This is because expansion coefficient of cap of cryovial is different from that of main body thereof in which the cap and the main body are made of different materials. As a result, specimens in the cryovials are damaged. Moreover, cryovials may explode when warming to room temperature after removing from liquid nitrogen container. Currently, as a solution to the above problem, thermally contractible films are employed to put on cryovials. Next, a sealing machine is employed to heat thermally contractible films to contract same. The cryovials are thus sealed by the thermally contractible films. As a result, the liquid nitrogen permeation is avoided.
Taiwanese Invention Patent No. 271,816 discloses an apparatus for sealing cryovial as shown in FIGS. 1 to 3. The apparatus comprises a mount A, a heating and blowing unit B on a top of the mount A, a motor C in a lower part of the mount A, a vertical chain C1 driven by the motor C to move cyclically, a threaded rod D1 provided on the mount A and disposed between the heating and blowing unit B and the motor C, a platform D2 slidably provided on the threaded rod D1, a link C2 extending from an underside of the platform D2 to a top of the chain C1 such that the platform D2 is adapted to move vertically along the threaded rod D1 as driven by the motor C and the drain C1, a second motor D4 secured to the underside of the platform D2 and having a rotating shaft D5 upwardly passed through the platform D2, a holder D3 secured to the shaft D5 and adapted to firmly hold a bottom of a body F2 of a cryovial F with cap F1 and thermally contractible film F3 disposed externally of the holder D3, an axis of the shaft D5 being aligned with and connected to a length axis of the cryovial F such that the holder D3 and the cryovial F held by the holder D3 are adapted to rotate about a length axis of the cryovial F when the motor D4 activates, a controller (not shown) having circuitry electrically connected to the motor C, the second motor D4, and the heating and blowing unit B such that enabling the controller by turning on a switch (not shown) will activate the motor C, the second motor D4, and the heating and blowing unit B.
In operation, specimens are contained in the cryovial F and the thermally contractible film F3 is put on the cryovial F prior to being fastened by the holder D3. Next, activate the motor C to move both the second motor D4 and the holder D3 from the current position to a heating position to be heated for a predetermined period of time in cooperation with the chain C1, the link C2, and the platform D2. Next, stop the motor C and activate the second motor D4 to turn the holder D3. At the same time, the heating and blowing unit B heats the thermally contractible film F3. The thermally contractible film F3 thus contracts to fasten a joining portion of the cap F1 and the body F2. Stop the heating and blowing unit B and the second motor D4 immediately after the completion of the heating. Next, activates the motor C again to move both the second motor D4 and the holder D3 back to the original positions. Finally, remove the sealed cryovial F from the holder D3.
But this is unsatisfactory for the purpose for which the invention is concerned for the following reasons: The platform D2 is adapted to move vertically along the threaded rod D1. Further, a maximum moving distance of the platform D2 is limited due to the mechanism of the cooperating chain C1 and the link C2. As such, only cryovials of the same size are applicable to this apparatus. This can greatly limit applications of the apparatus and thus the sealing of cryovials. Thus, a need for improvement exists in order to overcome the inadequacies of the prior art and contributes significantly to the advancement of the art.